Telephone-exchange system



' Sept. 1, 1926. 1,598,918

G. A. E. LUNDELL TELEPHONE EXCHANGE SYSTEM Original Fil 'l April 1, 1921 a Sheets-Sheet 1 Q Oo ooC O 2 onoO C D awueutoz I 7 @Mmm 7 ,I G.A.E.LUNDELL TELEPHONE EXCHANGE SYSTEM Original Filed April 1,

1921 3 Sheets-Sheet 2 nvcouon awwwntoz m3 mmw C T Sept. 7, 1926. {1598;918

' G. A. E LUNDELL TELEPHONE EXCHANGE SYSTEM Original Filed April 1921 s Sheets-Sheet s Patented Sept. 7, 1926.

UNITED- STATES GEORGE ALBEN E. LUNDELL, OF NEW YORK, N. Y.

1 TELEPHONE-EXCHANGE SYSTEM.

Application filed April 1, 1921, Serial No. 457,756. Renewed November 18 1925.

This invention relates to telephone exchange systems, and more particularly to party line station signalling, in such systems.

The object of the present invention is to provide improved means for selecting a desired one of the stationsof a poly-station line. I

My invention is more particularly adapted for exchange systems in which selectors areemployed for the establishment of telephonic connections. According to one feature thereof, a single selecting commutator of a selector mechanism-is employed both to control selection of the wanted line terminals, and further to control the selection of signalling current suitable to signal the wanted station.

According to another feature of the present invention a single set of line terminals represent the called lineson the final selector, independent of the number of stations on the line.

According to another feature, selection of one of the stations proceeds in the same manner as for a single station line,. while selection of another station of the same line causes the register sender control mechanism to subtract one impulse from the final selector group selectingimpulsesand to add to the impulses for individual terminal selection a number of impulses equivalent'to the. number of sets of terminals contained in one group. Thus the final selector reaches the same set of line terminals in each case.

Another feature relates to the provision of recording mechanism:associated with the final selector, whereby actuation of the final selector to make connection to a line by units selecting impulses greater in number than the number of sets of terminals contained in one group causes selection of a predetermined station on :1 called polystation line.

Other objects will appear as the descrip tion of the invention rogresses.

V The present disclosure is one of a variety of forms in which the invention may be practiced, but it is understood that the scope of the invention is not to be determined by it, reference being had to the appended claims for that purpose.

Referring to the drawings, Figures 1, 2, 3 and tfshow somuch -of;-=a telephone exchange system as isnecessary to an understanding of the invention;

Figure 1 shows a calling line and a first selector switch; 1

Figure 2 shows a plurality of called lines and a final selector for establishing connections with the terminals thereof, and should be placed to the right of Figure 1;

Figure 3 shows a register sender adapted to control the selectors of Figures 1 and 2 and should be placed below Figure l;

Figure l shows a modification of the register device of Figure 2, whereby a greater number of party line stationsmay bese lected.

Referring. to Figure 1 the calling subscribers station is joined to the central office by conductors 12, 13. Line finder 14 represents a form of mechanism for connecting a calling line with an idle first selector 15.. Such mechanisms are well known in the art.

The calling party removes his receiver from its hook, and closes a circuit: ground, right hand winding of relay 16, right hand contact of relay l7, conductor 12, substation 11, conductor 13, left handwinding of relay 16, to grounded battery. Relay 16 operates and connects a hunting test potential from a source of energy 18 to the test conductor. Relay 17 is difi'erentialand does not operate. ground, right hand contact of relay 16, con- A circuit is now Closed from ductor 19, sequence switch contact 20, power magnet 21 to grounded battery.

Thepower magnet 21 forms part of a se-- quence switch mechanism comprising sets of contacts such as 20 adapted to close contacts in the various positions of the sequence switch. The numerals which appear adjacent to the sequence switch contacts in the several parts of the drawings, indicate the positions of the sequence switch at which these contacts are closed; with the exception that the centering springs, one of which appears immediately above the power magnet of each switch, are open only at the positions indicated by the numerals adjacent thereto and therefore the sequence switches can stop .only in these positions. Motor mechanism is provided for rotating the sequence switch through 1ts successive positions. "This mechanism is employed dur ng the ,energization of the power magnet for driving the se-.

quence switch.

.VVhile passing from. positions lto 3 of the sequence switch of Figure 1, wipers 22, 23,- 24 of line. finder 1 1 are set on the terminals of the calling-line. Conductors. 25,

number of the wanted line.

26 may extend in any suitable manner to a register sender such as shown in Figure 3.

In position 2 of the sequence switch a guarding potential is placed on the test wire of the calling line, by way of sequence switch contact 30, resistance 31, a source of current 32. This potential energizes the left hand winding of relay 17 which relay operates and cuts off relay 16. The armatures of relay 16 are retracted.

In position 3 of the same sequence switch, a circuit is closed from grounded battery (see Figure 3) left hand winding of relay 27, conductor 25, sequence switch contact 28, wiper 23, conductor 13, substation 11, conductor 12, wiper 24, sequence switch contact 29. conductor 26, right hand winding of relay 27 to ground. Relay 27 operates.

The calling subscriber now manipulates the calling device 33 in accordance with the Assuming that he desires to call station 34, and that the designating number thereof is 213, the calling device is operated to open the line twicepauseagain open the line 0nce pauseand finally to open the line three times.

Relay 27 and its associated slow release relays 35, 36 are adapted to control register switches 37, 38, 39, 40 and steering switch 41. Register 37 consists of magnet 42, whose armature upon its each release moves a ratchet wheel 43 and the wiper arms 44, 45 in a clockwise direction. Said arms 44, 45 each contact sequentially with a circular row of contacts. and when said arms are stepped off the last contacts in their respective rows, they again contact with-the first or normal contacts.

Similarly register 38 comprises the ma net 46, ratchet wheel 47, wiper arms 43. 4 register 39 the magnet 50 ratchet wheel 51 wiper arms 52, 53; register 40 the magnet 54. ratchet wheel 55. wiper arms 56, 57; and steering switch 41 the n'iagnet 5S, ratchet wheel 59 and arms 60, 61, 62.

The setting of the registers by the calling device 33 in the present instance brings arms 44. 45 to their respective third contacts; arms 48, 49 to their second contacts and arms 52, 53 to their fourth contacts. Arms 56, 57 are not yet moved. since the called line 34 is a single station line and no party line sufiix is included in its designating number.

As soon as the subscriber has sent in the impulses for the first digit the steering switch 41 is actuated and so on successively for each digit. \Vhen the three digits in the present called number have been transmitted and recorded, arms 60, 61, 62 are ad- 'vanced to their respective fourth contacts. A circuitis now closed from ground, wiper arm 62, winding of relay 63, sequence switch contact 64 to grounded battery. Sequence switch contact 64 shown in Figure 3, and other contacts on that sheet, form part of a sequence switch actuated by the power magnet 66.

Relay 63 operates and closes a circuit fom ground, right hand contact of this relay, conductor (37, sequence switch contact 63,.power magnet 66 to grounded battery, and under control of centering spring (39 the sequence switch advances to position 2.

A circuit is now closed from ground, left hand back contact of relay 70, winding of relay 7 2, sequence switch contact 73, conductor 7 4, sequence switch contact 75, conductor 76, winding of relay 77 to grounded battery. Relays 72 and 77 operate. Relay 77 closes a locking circuit for itself by way of conductor 78 independent of conductor 76. Relay 72 closes a circuit from ground, sequence switch contact 79. conductor 80, arm 44, conductor 81, armature and back contact of relay 173, armature and back contact of relay 82, winding of relay 83, conductor 34 to grounded battery. Relay 83 operates and prepares a locking circuit for itself, but

said locking circuit is at this time not energized on account of the short circuit by way of the armature and front contact of relay 72. A circuit is closed from ground, left hand armature and front contact 01" relay 7'7, conductor 85, sequence switch contact 86, power magnet 21 and the sequence switch of Figure 1 moves out of position 3 and into position 4. A circuit is now closed from ground. left hand armature and front contact of relay 77. conductor 35, sequence switch contat 87. dr ving magnet 33 to grounded battery. lVipers 89, 90, 91 and connnutatcr brush 92 are advanced. Brush contacts during such advancement with conducting and insulating portions of a commutator plate Upon striking the tirst conducting portion relay 72 is short circuited, and upon releasing. removes in turn the circuit around the winding of relay 32 and this relay operates. Relays 77 and 33 remain operated. Upon striking the next insulating portion relays 72 and 94 operate. Upon the brush 92 striking the second conducting portion relay 72 releases and relay operates. Upon striking the insulating portirn beyond. no circuit prevails for maintaining relay 77 operated, and this relay releases and deenergizes driving magnet stopping wipers 39, 90. 91 and brush 92. A retaining pawl 95 maintains the brush support in its po ition. A circuit is closed from ground, left hand back contact of relay 77, sequence switch contact 36, power magnet 21 to grounsiled batte for moving the sequence switch out of position 4.

An idle trunk may now be seized in any well known manner, in position 7 of the se .quence switch, after which the sequence switch'moves to position 10. A guarding potential is placed on the test wire 158 of the selected trunk, over sequence switch contact 156, closing the circuit of the winding of relay 157, and operating this relay. 7

The operation of relay closes the following c1rcuit: ground, right hand armature and front contact of this relay, conductor 96, sequence switch contact 68, power magnet 66 to grounded battery, moving the sequence switch of Figure 3 into position 3.

When relay 63 operated, a circuit was also closed from ground, pulsator 97, left hand front contact of relay 63, conductor 98, to the beginning of a chain of relays such as 99, 100. As the pulsator opens and closes its circuit, the relays ofthis chain operate in sequence, and at the end of a predetermined interval, relay 100 operates. A circuit is then closed from ground, left hand armature and front contact of relay 100, middle contact of relay 63, sequence switch contact 68, power magnet 66 to grounded'battery. The sequence switch of Figure 3 moves out of position 3, and under control of centering spring 69 into position 5. Relays 63,83, 82,

.94, 70 and the chain extending from 99 to 100 release, their energizing circuits being broken at sequence switch contact 103. A circuit is closed fromground, left hand armature and back contact of relay 70, winding of relay 72, sequence switch contact 7 3, conductor 74, sequence switch contact 75, conductor 104, wiper 91, conductor 105, sequence switch contact 106 of Figure 2, conuctor 107, winding. of relay 108 to grounded.

battery. The sequence switch contacts shown on Figure 2 form part of a sequence switch actuated by the power magnet 110.

Relays 108 and 72 operate. Relay 108 closes a locking circuit for itself by way of conductor ,109 independent of the conductor 107.v Relay 72 closes a circuit from ground, sequence switch contact 79, conductor 112, arm 48, conductor 113, right hand back contact and armature of relay 174, winding .of relay 94, to grounded battery. Relay 94 opcrates and closes a locking circuit for itself,

but said locking circuit is at this time not energized on account ofthe short circuit by way of the armature and front contact of relay 72.

A circuit is closed from ground, right hand armature and front contact ofv relay 108, conductorv 114, sequence switch contact 115,

power magnet 110 to grounded battery. The

sequence switch of Figure 2 moves from position 1 to 2, under control of centering spring 1163' A circuit is then closed from ground,r1ght hand armature and front contact of relay 108, conductor 114, sequence switch contact 117, driving magnet 118 to grounded battery, operating the magnet 11.8. Wipers, 119, 120, 121 and commutator brushes 122, 123are advanced. Brushes 122 and 123 contact during such advancement with conducting and lnsulating portlons of commutator bars 124 and 125 respectively.

lVhen brush 123 strikes the first conducting portion of commutator bar 125 relay 72 is short circuited, and releases,thus removing right hand armature and back contact of relay 108, conductor 127, sequence switch contact 115, power magnet 110 to grounded battery, moving the sequence switch of Figure 2 out of position 2, and under control of its centering spring 116 into position 3. The operation of relay 70 closes the following circuit: ground, right hand armature and front contact of this relay, conductor 96, sequence switch contact 68, power magnet 66 to grounded battery, moving the sequence switch of Figure 3 out of position 5 and into position 7, under control of centering spring 69. Relays 94, 70 release, their energizing circuit having been broken at sequence switch contact 103. A circuit is closed from ground, left hand armature and back contact of relay 70, winding of relay 72, sequence, switch contact 73, conductor 74, se quence switch contact .7 5, conductor 104, wiper arm.9 1, conductor 105,.sequence switch contact 106, conductor 107, winding of relay 108 to grounded battery. Relays 108 and 72 operate. Relay108 closes a locking circuit for itself as before. Relay-72 closes a circuit from ground, armature and front contact of this relay, sequence switch contact 79, conductor 128, arm 52, conductor 129, armature and back contact of relay 130, winding of relay 131, conductor 84't-o grounded battery. Relay 131 operates and closes a locking circuit for itself but said locking circuit is at this time not energized on account of the short circuit by way of the armature and front contact of relay 72. V

A circuit is closed from ground. right hand armatureand front contact of relay 108, conductor 114;, sequence switch contact 115, power magnet to grounded battery. The sequence switch of Figure 2 moves from position 3 and under control of its centering spring 116'into position 5. In positions 4- and. 5. the following circuit is closed: ground, right hand armature and front contact of relay 108, conductor 114, sequence switch contact 117, driving magnet 118 to 1 23fare. a ain advanced. Forv each. set of terminals passed by wipers 119, 120, 121 the brush 122 makes and breaks once the circuit from ground, brush 122, conducting portion of commutator bar 12 1, conductor and thus intermittently short circuits the relay 72. Relays 130, 83, 82, 9i and 70 operate in order, and finally the circuit of relay 108 is entirely open and this relay releases, magnet 118 deenergizes and wipers 119, 120, 121 stop on the line terminals corresponding in number to the setting or the register 39, that is to say, the number of the wanted line.

Relay 70 being operated, a circuit is closed from ground, right hand armature and troutcoutact of this relay, conductor 96. sequence switch contact 68, sequence switch magnet 66 to grounded battery, and the sequence switch of Figure 3 mores to position 1 under control of its centering spring 69. Relays 131, 130, 83, 82, 94-, 70 release. their eu-- ergizing circuits being open at sequence switch contact 103. in position 12 to 1 a circuit closed from ground, sequence switch contact 103 of Figure 3, conductor 135, sequence switch contact 86, power magnet 21 to grounded battery. The sequence switch of Figure 1 mores from positions to 13. Sequence switch contacts 28 and 29 break the circuit to conductors 25, 26 and re.ays 27, release. A circuit is then closed for returning switches ll, 37, 38, the re turn circuit comprising arms 61, 15, 49, 53. A circuit is closed from ground, winding repeating coil 136, conductor 137, sequence switch contact 29, wiper 24, conductor 12, substation 11, conductor 13, wiper .3. se quence switch contact 28, winding of relay 138, winding of repeating coil 136 to ground-- ed battery. Relay 138 operates and closes a. local circuit through the winding of relay Relay 139 operates.

The release of relay 108, as described, closes the following circuit: ground.- right hand armature and back contact of relay 108, conductor 12?, sequence switch contact 115, power magnet 110 to grounded battery. The sequence switch or" Figure 2 moves from position 5 to 12. In position 7, the usual busy test of the called. line may be made, and in positions 8 to 16 a guarding potential is applied to the test wire thereof by way of grounded battery. resistance 140, sequence switch contact 196, and wiper 119.

In position 12 a circuit is closed from ground, arinatiu'e and back contact of relay 1411, back contact and armature of relay 142-2, winding of relay 1 1%, sequence switch contact 187 to grounded battery. Relay 14% opcrates and closes a signalling circuit from grounded source of signalling current 11o, winding of relay 1&1, left hand front contact and armature of relay 1%, sequence switch contact 150, back contact and armature 149 of relay 1&8, wiper 120, signalling apparatus of substation 34, wiper 121, armature 1%? and back contact of relay 14:8, se quence switch contact 146, right hand ar mature and front contact of the relay M l to ground. Relay 14-1 is adjusted not to operate on the current flow. hen the called party answers the increase in current which results when his receiver is lifted, causes the operation of relay 1 11. Relay 1 12 there upon operates and in turn short circuits relay 14 1. Relay lets releases. A circuit is now closed from ground, winding of rc-- peating coil 136 of Figure 1, sequence switch contact 151, conductor 104e, wiper 91, conductor 105, sequence switch contact right hand back contact and armature of relay 1 91, sequence switch contact 146, back contact and armature of relay 148, wiper 121, substation 341, wiper 120, armature 14.?9 and back contact of relay 1&8, sequence switch contact 150, left hand armature and back contact of relay 144, sequence switch contact 153, conductor 154, wiper 90, sequence switch contact 155, winding of repeating coil 136 to grounded battery, eu ergizing the transmitter 0t substation 34 Elie subscribers are now connected for conversational purposes. tion is over, they replace their receivers on the hooks. In the present disclosure the selector switches are released when the calling subscriber replaces his receiver on its switch hook, the circuit of the relay 138 being thereby opened.

The circuits of relays 138, 139 are deenez-gized, and these relays release. A circuit is then closed from ground, armature and back contact of relay 139, sequence switch contact 20, power magnet 21 to grounded battery, moving the sequence switch of Fig ure 1 into position 18. Sequence switch contacts and 156 break the circuits of relays 1'7 and 157 respectively, and these relays release. Line finder mechanism 1 1 may be restored in any suitable manner.

A circuit is closed by way of ground, sequence switch contact 159 for energizing return magnet 160 and the actuation 0t this magnet withdraws pawl 95 and returns wipers 89, 90, 91 and brush 92 to normal. At normal, a circuit is closed from ground, brush 92, conductor 161, sequence switch contact 86, power magnet 21 to grounded battery, moving the sequence switch of Figure 1 into position 1. The circuit of magnet 160 is d-eenergized by the opening of sequence switch contact 159.

A circuit is also closed from ground, armature and back contact of relay 157, Figure 2, conductor 162, sequence switch contact 163, power magnet 110 to grounded battery, for moving the sequence switch of Figure 2 out of position 12 into position 18. The circuit of relay 1&2 is broken by sequence switch contact 187, and this relay releases. A circuit is closed from ground,

lVhen the conversa sequence switch contact 164, return magnetv 165 to grounded battery for energizing return'magnet 165, and the operation of this magnet withdraws pawl 126 and wipers 119,

' 120, 121 and brushes 122, 123 are returned to normal. At normal, a circuit is closed from ground, brush 123, conductor 166, sequence switch contact 115, power magnet 110 to grounded battery, moving the sequence switch of Figure 2, into position 1. The circuit of magnet 165 is cleenergized by the opening of sequence'switch contact 164.

The apparatus of Fi ures '1, 2 and 3 is now fully restored to normal and'ready for telephonic connection to the terminals of line 168. In doingthis the wipers of selector 169 are adv'ancedduri'ng group selection (position 2 of the sequence switch of Fig ure 2) over theter minals ofthe first group,- and in position 5 over the individual or units terminals. V

The signalling circuit for signalling called station 167, in position 12 of Figure 2, is as follows: a grounded source 145 of'signalling current, winding of relay 141,le'ft hand contact and armature of relay 144, sequence switch contact-150, back contact and armature 149 of relay 148, wiper 120, conductor 168 of the called line, signalling apparatus of station 167 to ground. The signalling apparatus of station 170 is'at this time short circuited' by the ground at the right hand front contact and armature of relay 144 and sequence switch contact 146, and is therefore inactive. The attention of the wanted-party is'attractcd and he responds by removing his receiver. Conversation and disconnection is the same as'pr'eviously described.

Assuming a call for station 170, such station is known to the public by. some such number as 2222,t he last'digit being the party line sutfix. Manipulation of thecalling device 33 according to this number sets the arms of registers137, 38, '39, 40 on the third contacts thereof, in accordance with the said number. i

As soon as the calling party sends in the fourth set of impulses, steering switch 41 moves into its fifth position. Relay 63 releases, but a circuit is'clos'fed from ground, wiper arm 62, sequence switch contact 68,

power magnet 66 to grounded battery, in.

dependent of tlie'conta ct of said'relay; I The is broken when the arm62 moves out of its fourth position, and thus relay 63 releases. So much of there-lay chain 99 100 as is operated at the time relay 63 releases, remains so operated until deenergized by'the subsequent breaking of the locking circuit at sequence switch contact 103.

The operation. of the selector shown in Fig. 1 and of the sender shown in Fig. 3 with'the sender sequence switchin position 2 is the same as before. The sequence switchof'Figuie 3 moves out of position 2 into "position 3 in the manner previously described. Said sequence switch moves out of position 3 by virtue of a circuit from ground, arm 62 on its fifth contact, sequence switch contact 68, powermagnet 66 to grounded battery, independent of the chain 99 100. The sequence switch, under control of centering spring 69 moves to posi tion 5. Relays 131, 130, 83, 82, 94, 70, and chain 99 100 release, their energizing circuits being broken at sequence switch con tact 103.

Relay 173 now operates, itscircuit comprising ground, arm '56 on its third contact, conductor 172, sequenceswitch contact 171, winding of relay 173 to grounded battery.

A circuit is closed from ground, left hand armature and backcontactof relay 70, winding of relay 72, sequence switch contact 73,

conductor 74, sequence switch contact 7 5, conductor 104, wiper 91, conductor 105, sequence switch contact 106 of Figure. 2, eonductor 107, winding ofrelay 108'to grounded battery. Relays 108 and 72 operate. Relay 72 closes 'a circuit from ground, sequence switch contact '79, conductor 112, arm 48, conductor 81, armature and frontcontact of relay 173-, right hand back contact and armature of relay 174, winding of relay 94 to grounded battery. Relay 94 op erates and closes an unenergized locking circuit for itself as before. Thus the number of group impulsespermitted to be sent to theselector of Figure 2 is one less than the number corresponding to the setting ofthe register 38. Theselector of 'Figure 2 is thus stopped in a position at the beginning of the group previous to'that in which the called'line appears. c a

After the sending of the last group impulse relay 70 operates and relay 108 releases as above described; A circuit is closed by way of conductor 127 and sequence switch sequence switch of Figure 2 moves to =posi tion 3. A circuit is also closed from ground, right hand armatureand front contact of relay 70, sequence switc'h contact 68, power magnet, 66, .to grounded battery,energi zing the power magnet 66. Ihe sequence switch of Figure'3 moves to position 7.. Relays 173, 94, 70 release, their energizingcircuits circuit ofthewin'ding of the said relay 63being broken at sequence switch contacts'l7l 12:) contact 115 for powermagnet 11 0 andthe and 103. A circuit is closed from ground, arm 56, conductor 172, sequence switch contact 171, winding of relay 174 to grounded battery, operating relay 174 for a purpose to be subsequently set forth. A circuit is closed from ground, left hand armature and back contact of relay 70, winding of relay 72, sequence switch contact 73, conductor 74, sequence switch contact 75, conductor 104 wiper 91, conductor 105, sequence switch contact 106, conductor 107, winding of relay 108 to grounded battery. Relays 108 and 72 operate. Relay 72 closes a circuit from ground, armature and front contact of this relay, sequence switch contact 79, conductor 128, arm 52, conductor 81, armature and back contact of relay 173, armature and back contact of relay 82, winding of relay 83, conductor 84 to grounded battery. Relay 83 operates. As the selector advances (Figure 2), short circuiting impulses are transmitted over conductor 105, and relay 72 intermittently operates. Thus relay 82 operates. The circuit of the contact of relay 72 is connected through the front contact of relay 82, left hand front contact and armature of relay 174, left hand back contact and armature of relay 63, conductor 98, winding of relay 99 to grounded battery. There are as many pairs of relays in the chain 99 100, inclusive, as there are sets of terminals in a group of the selector of Figure 2. Thus on the present call there is added to the series of impulses for individual terminal selection the number of impulses equal to the number of sets of terminals in a group, this being in addition to the number of impulses corresponding to the setting of the register 39. Thus the de ficiency in group selection due to subtracting one group impulse is made up, and wipers 119, 120, 121 are advanced to the same set of terminals as on the call for station 167. In doing so, brush 123 necessarily passes a conducting portion of the commutator bar 125, this being the conducting portion at the beginning of the group in which the wanted line terminals appear, and which was employed for transmitting the last short circuiting impulse on the call for station 167 but not employed for that purpose on the present call.

A momentary circuit is thus closed from ground, brush 123, conducting portion of bar 125, conductor 178, sequence switch contact 179, winding of relay 148, resistance 180 to grounded battery. Relay 148 operates and closes a locking circuit for itself independent of brush 123, by way of its armature 181 and front contact and sequence switch contact 188. V

The restoration of the apparatus of Figure 3 and the advancement of the sequence switch of Figure 1 to position 13 is the sameas previously described. The release of relay 108 closes a circuit over conductor 127 and sequence switch contact for energizing power magnet 110 and the sequence switch of Figure 2 is moved out of position 5 and under control of its centering spring 116 into position 12. Relay 148 being operated, the circuit of wipers 120, 121 is held open at armature 147, 149. A circuit is closed from ground, armature 182 and front contact of relay 148, conductor 183, sequence switch contact 115, power magnet 110 to grounded battery, for moving the sequence switch of Figure 2 through position 12. Under control of its centering spring 116 it moves to position 14. cuit of relay 148 is broken at sequence switch contact 188, and this relay releases.

The signalling circuit now closed comprises a grounded source of signalling current, winding of marginal relay 141, left hand front contact and armature of relay 144, sequence switch contact 146, back contact and armature 147 of relay 148, wiper 121, a conductor 185 of the called line, signalling apparatus of wanted station 170 to ground. The signalling apparatus of station 167 is at this time short circuited by the ground at the right hand front contact and armature of relay 144 and sequence switch contact 150, and is therefore inactive. The attention of the wanted party is attracted by the actuation of his signalling appa ratus, and he responds by removing his receiver. Conversation and disconnection is the same as before.

It will be seen that I have provided a party line ringing system of simple, efficient and novel form. Broadly expressed, the principle employed is that of selecting one station of a wanted poly-station line by the same method as is used for a single station line, i. e. by selecting the group containing the wanted line terminals and then the individual set of terminals thereof, and selecting a different station by subtraction of a predetermined number of impulses from group selection and adding a corresponding number, multiplied by the number of sets of terminals in each group, to the individual or units selecting impulses, and employing a recording means at the selector to register the number of groups passed over during units selection and select a selective signalling station accordingly.

It will be readily understood that the system of the present invention may readily be extended to provide for any desired number of stations less than the number of groups in selector 169. There is shown in Figure 4, a modification providing for four stations on a line. he register mechanism consists of the step by step switch and includes magnet 189, ratchet wheel 190, arms 191, 192, 247, 249. The ratchet wheel and the arms 191, 192, 247, 249 are moved The energizing cirloo one step in .a counter clockwise direction for each retraction of the magnet 189. Said arms contact sequentially with circular rows of contacts, and when stepped off the last contacts, again contact with the-first or normal contacts. Reference characters greater than 200 correspond in function with reference characters of Figure 2 having thev same tens and units numerals.

A source of variously characterized current is shown at 245,being adapted to produce either pulsating currents or alternating currents of different frequency for the harmonic. system of party line ringing. For each preliminary-group passed bythe brush 123 in position 5 of the sequence switch, one impulse is transmitted to magnet 189, stepping ratchet wheel 190 and the arms 191, 192, 241,249 one step in a counter clockwise direction. The arm 192 subsequently controlsthe power magnet 110 to movethe sequence switch into one of a plurality of talking positions, sequence switch contact 193 co-acting with it for that purpose. Sequence switch contact 194- determines the selection of the character of current. Arms 247, 2&9 and sequence switch contacts 246, 250 prevent the closure of the circuits of wipers 120,121 until the sequence switch is in the proper talking position, After conversation, the register mechanism 248 is restored by means of sequence switch contact 193. V

In the modification shown in Fig. 1 as applied to .a selector switch circuit of Fi 2, when a calling party on the line requiring the connector to step over a plurality of connected groups is desired, the connector is stopped subsequent to the tens digits selection in such position that the wipers 119, 120 and 121 are temporarily positioned at the beginning of agroup spaced apart'from the group in which the selected line appears. "This spacing depends upon the particular station desired to be called and may comprise one or more groups of lines. The sequence switch 110 is then advanced, as has been described, into positions 4 and 5 and in position 5 the selectionof the units digits takes place in the manner already described, there being added to the units a sufiicient number of impulses to cause wipers 119, 120 and 121 to pass over intermediate groups and make final selection in the group of lines in which the desired line terminals appear. Thus there is added to the series of impulses for individual terminal selection a number of impulses equal to the number of spaces and terminals in the groups passed over,

thus putting in an additional number ofimpulses corresponding to the units digits as set up in the register 39. Thus the deficiency in the group selection due to sub tracting a predetermined number of group impulses is made up and the wipers 119,

120 and 121 are advanced to the sameset of terminals as if no group impulses had been subtracted;

' It is understood that no polystation line can be connected to a set of terminals in the first group of selector 169, as it is necessary in selecting such lines to subtract an impulse from the group selecting impulses, and the first group is selected by only a single impulse. not be below the fourth group. It is also desirable that no poly-station line be connected to the last set of terminals in any group, as in calling such a line, the brush 128 remains ]I1 contact with a conducting portion of commutator bar 125 during con-- versation. The circuit of Figure 2 is arranged to employ on such calls the signalling current for single station lines, and, that of Figure 4 thecurrent used for the second stations.

lVh-at is. claimed is:-"

1. In an automatic telephone exchange system, called lines arranged in groups, a

selector switch adapted to select said called lines in groups, means for selecting a group initting between said selector switch and said register sender group selecting and in dividual terminal selecting impulses, means for subtracting from the series of group selecting impulses a predetermined number of impulses and means for adding to the series of individual terminal selecting impulses a number of impulses to advance said selector a distance equivalent to that corresponding to the subtracted group impulses.

3. In a telephone exchange system, called poly-station lines arranged in groups, a. se-

Similarly, four party lines should lector switch adapted to select said called' lines in groups, means for selecting a group in advance of the group containing a wanted line, means for subsequently advancing said switch through intermediate groups to the wanted line, and recording mechanism responsive to said subsequent advancement for recording the number of intermediate groups passed over. v

4:. In a telephone exchange system, called poly-station lines arranged. in groups, one of said lines having a plurality of stations comprising variously characterized selective ringing apparatus, a selector switch adapted to select said called lines in groups, means tor selecting a group 111 advance of the group containing a wanted line. means for subsequently advancing said switch through intermediate groups to the wanted line, recording mechanism responsive to said subsequent advancement for recording the number of intermediate groups passed over and means selectively actuated by said recording mechanism for predetermining the station to be selectively signalled.

5. In a selector switch, a called line having a plurality of selectively actuated stations, said switch including a single contact maker for determining the station to be actuated and the degree of movement over said lines oi said switch.

6. In a selector switch, called lines arranged in sequential groups, one of said lines havin a plurality of stations each comprising selective signalling apparatus, said switch including a single contact making means for limiting selective movementof said switch, and for determining the station to be selectively actuated.

7. In a telephone exchange system, called lines arranged in groups, a selector switc adapted to select one of said called lines, saic; called line having a plurality of selectively signalled stations, a register sender for controlling said selector comprising a register adjustable according to the group in which said wanted line appears and comprising also a register adjustable according to the location of the wanted line in its group, means for transmitting between said selector switch and said register sender group selecting and individual terminal selecting impulses, means for subtracting "from the series of group selecting impulses a predetermined number of impulses, means for adding to the series of individual terminal selecting impulses a number of impulses equal in number to the number of sets of terminals contained in the subtracted number of groups and means actuated during transmission of said additional impulses for selectively actuating a wanted station on said line.

8. In an automatic telephone exchange system, called lines arranged in groups, a selector switch adapted to select said called lines in groups, means for selecting a group in advance of the group containing the wanted line, and means for subsequently advancing said switch through said group into a subsequent group.

9. In a telephone exchange system, called lines arranged in groups, a selector switch lncluding movable brushes adapted to select: one of said lines, a controller for selectnw a group of lines in advance of the group containing the wanted line, and means controlled by the extent of subsequent movement of said brushes to reach the Wanted linefor selectively controlling the character or" ringing current to be applied to said line.

10. In a telephone exchange system, called lines arranged in groups, a selector switch adapted to select said called lines in groups, means for selecting a group in advance of a group containing the wanted line, means for subsequently advancing said switch through intermediate groups to the wanted line, and selecting mechanism controlled by the extent ot subsequent movement.

. 11. In telephone exchange system, called hnes arranged in groups, a selector switch adapted to select said called lines in groups and including a circuit controlling device, means for selecting a group in advance of a group containing the wanted line, means for subsequently advancing said switch through intermediate groups to the wanted line and selecting mechanism operated bv said circuit controlling device in accord ance with the extent of subsequent movement of the selector switch.

In testimony whereof, I have hereunto set my hand this 30 day of March 1921.

GEORGE ALBEN E. LUNDELL. 

